Capacitor Fumed In EVEREADY LED Batten MODEL LBT-4FP
This LED Batten is around six –seven years old and was fit inside my service room. This batten is among the three that I have fit in the service room, as we, the technicians know that we need proper lighting to carry out our service work. All the three lights are switched on only when proper lighting was necessary from all sides to carry out the work on a set like a CRT TV that might block light. While I was doing some work in my computer, I heard a pop sound and fumes started emanating from this light fit high above in the front wall and it went off. I switched off the power and left it as I had some other pressing work and used the other lights for a few days until I found time and mood to bring this down for investigation.
With the help of a ladder, I managed to climb up, disconnect the wires and remove the batten. Took it out for a thorough clean and brought it to my service table. Upon removing the side cap and pulling out the LED strip, I could bring the LED driver module out. The Fixed cap was found charred, value of which could not be gathered. Two low value resistors at the AC input were also found burnt. There were 96 LEDs. The driver IC number was BP2328D, the datasheet of which can be downloaded from https://datasheetspdf.com/pdf-file/1304143/BPS/BP2328DJ/1 Following pictures would be of help to know the construction of this batten:
I checked a few LEDs using my analogue multimeter and found these to be ok. Then I used my LED checker and found the LED Strip to be working and got a reading of 66.2V. Typically, 96 LEDs worked with 66.2V, which need not be accurate due to over current drawn. If the LED was of 3V, it can consume around 288V. But this must be comibation of series connections and might be of some 1.5V rated. Well, I did not bother to investiage on this much! Since an 80V capacitor was used, the voltage has to be well within that!
Then I turned my attention to the driver circuit. I removed the charred cap and burnt resistors and cleaned the PCB thoroughly using IPA ensuring that it does not enter the coils and spoil it. I checked the only one electrolytic capacitor, 100uF/80V and found both ESR and value out:
My techie friends advised me to use a 1uF high voltage fixed cap to smoothen the DC and I used 105/450V capacitor. I was not having the 100uF/80V small size capacitor. So, I used a 100uF/160V cap and kept it straight so that the case of the batten can ‘swallow’ the driver unit! Just see the following pictures:
When I applied the power I got an output of 129.2V without load and 74.2V on connecting the LED strip with a 0.235A current drawn. Then to place the LED driver at the center of the case and pull out the AC input wires, I inserted a single strand wire through the hole in the center, taped it to the AC input wire and pulled, dragging the driver inside to its original place. There was no way of opening the bottom or top cover as these were bonded by some glue and further the case was so flimsy, it might get torn.
After this, I applied power and allowed it to be on for some time on my table and found it to be working very well. In order to meet the unlikely event of a failure and need to remove it standing on the ladder balancing and craning my neck at my old age, I used a two pin plug and socket in place of direct connection to the AC outlet. Following pictures would help you all to follow the descriptions:
Mission accomplished and satisfaction was only too glad to jump into the bag!
Here is the picture of the defective components as a finale:
P.S. Please use cntrl + scroll to zoom in/out pictures!
This article was prepared for you by Parasuraman Subramanian from India. He is 72 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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You may check on his previous article on Bridge Rectifier And IGBT Found Blown In BUTTERFLY Induction Cooker Model RHINO